The present invention relates to new substituted 2,6-diaminotoluene compounds of the general formula I, processes for their preparation, and coloring agents which contain these compounds for use on keratin fibers.
So-called oxidation dyes which are formed by oxidative coupling of development components (such as, for example, p-phenylenediamines, p-aminophenols or p-diaminopyridines) with coupling components (such as, for example, phenols, resorcinols, m-aminophenols, m-phenylenediamines, naphthols or pyrazolones) are of particular importance for dyeing hair. Under the conditions of use (e.g., low dyeing temperature and short dyeing time), they produce intensive colors with very good fastness properties. Oxidation dyes also play an important role in dyeing fur. Suitable oxidation dyestuff precursors must primarily meet the following prerequirements for use: during oxidative coupling of the particular coupling and development components, they must produce the desired color (which should have a good absorption and migrating capacity on hair or fur) to an adequate intensity. The dyestuffs formed must be generally stable (especially to heat) and specifically resistant to washing, light, and perspiration. In particular, they should not lead to shifts in the color of the original shade under wearing conditions. Moreover, they should be toxicologically and dermatologically acceptable.
These requirements cannot always be made to coincide. This is particularly clear in the field of so-called blue couplers. With 2,6-diaminotoluene, as the prior art, there exists a compound which on the one hand is not completely satisfactory during use because the stability of the color of the dyed hair is not satisfactory (for example, under the action of perspiration, acid rain, detergents, sunlight, UV radiation and the like), and on the other hand is also questionable from the toxicological point of view.
JP 51-124,194 A (1976) discloses the compound N-(2-hydroxyethyl)-2,6-toluylenediamine, which is caused to react with maleic anhydride to polyimide resins. DE 30 45 959 A1 describes the use of N-hydroxyalkyl-substituted m-phenylendiamines of the general formula ##STR2## wherein R denotes a hydroxyalkyl radical with 1-4 carbon atoms and 1 or 2 hydroxyl groups as coupler component in agents for oxidative dyeing of hair to produce green to black-blue color shades. Example 4 of DE 2,449,101 1 A1 (U.S. Pat. Nos. 4,092,102 and 4,196,145) discloses the preparation of 2-hydroxyethylamino-4-aminotoluene and dyeing tests of this compound in combination with p-phenylenediamine or p-toluenediaminesulfate in agents for oxidative dyeing of hair; deep blue color shades are the result of this example. DE-3,137,473 A1 refers to 2,4-diamino-m-xylene of the general formula ##STR3## in which one of the substitutents R.sup.1 or R.sup.2 is a hydrogen atom and the other substituent denotes an alkyl group with 1-4 carbon atoms or a substituted alkyl group. These compounds should give, in agents for oxidative dyeing of hair, green-grey, red-brown, black-blue or dark-violet shades.